Interpretive Summary: The effective use of plant germplasm for an array of objectives including agriculture, conservation, restoration, landscaping, recreation, and bio-remediation requires knowledge of the adaptation of each species and more specifically, cultivars, strains, accessions, or ecotypes of a species to specific sites or regions. Since ecoregion and hardiness zone classification systems integrate many climatic and geographic variables that determine plant adaptation, they can be combined to develop Plant Adaptation Regions (PAR). Plant Adaptation Regions can be used to both characterize plant germplasm adaptation regions and the germplasm itself. The use of PAR's for native or non-crop activities such as rangeland and natural area restoration will enable the germplasm of an array of species to be assigned to areas for utilization even though extensive testing may not be feasible because of limited resources. The use of PAR's should allow plant germplasm evaluation resources to be used in a more effective manner by providing both a climatic and ecological mechanism for matching germplasm to intended areas of use. The example Plant Adaptation Region map of the contiguous USA developed for this report is based on widely used and understood climatic and ecological maps and can be used by plant scientists with or without GIS software.

Technical Abstract:
The effective use of plant germplasm for an array of objectives including agriculture, conservation, restoration, landscaping, recreation, and bio-remediation requires knowledge of the adaptation of each species and more specifically, cultivars, strains, accessions, or ecotypes of a species to specific sites or regions. In agronomic and horticultural crop production in which substantial research resources are often available, specific adaptation information has been developed by extensive testing. Other users of plant germplasm such as rangeland, grassland, park, and restoration project managers often lack the resources to determine plant germplasm adaptation because of the large number of species that are used and the extensive geographical areas that are serviced. Problems often arise in delineating adaptation areas for plant germplasm of both native and introduced species for collection, testing, and utilization. Since ecoregion and hardiness zone classification systems integrate many climatic and geographic variables that determine plant adaptation, they can be combined to develop Plant Adaptation Regions (PAR's). As an example, the northern and southern sections of eastern Nebraska, which are in Prairie Parkland Ecoregion Province No. 251, would be designated PAR 251-HZ4 and PAR 251-HZ5, respectively using Bailey's Ecoregion Provinces and the USDA Plant Hardiness Zones (HZ's). Ecoregion-hardiness zone analogs of these PAR's are found in other continents. PAR's can be used to both characterize plant germplasm adaptation regions and the germplasm itself. The utility of PAR's in germplasm collection and characterization was demonstrated with a collection of legumes native to the North American prairies.